A conventionally employed lens molding method for molding a lens includes pressing, against a resin material, a mold having a transfer surface for transferring a lens shape and curing the resin material in a state where the mold is pressed against this resin material. In this lens molding method, a molded lens is released from the mold after the resin material is cured. However, when the molded lens is released from the mold, the molded lens may be damaged due to adhesion between the lens and the transfer surface.
In order to solve the above problem, Patent Literature 1 discloses a technique for releasing a molded lens from a mold in a compound lens molding apparatus. According to this technique, as illustrated in FIG. 12, the molded lens is released from a mold 400, by applying a high-frequency voltage to the mold 400 and vibrating a molding surface 401 of the mold 400. In this method, the molding surface 401 undergoes elastic deformation and thereby an adhesion strength between the lens and the molding surface 401 can be decreased. Therefore, the molded lens may be safely released from the mold by the method.
Patent Literature 2 discloses a method for releasing a resin molded product from a mold with use of an ultrasonic wave. In Patent Literature 2, as illustrated in FIG. 13, a molded product 502 is molded by (i) first injecting resin such as epoxy resin having an adhesion effect into a mold 501 which is a casting mold exposed to the atmosphere and which has a cavity 501a and (ii) curing the resin by heating. After molding, a flat vibrator 503 is provided so as to be in direct contact with a top surface of the molded product 502. Then, vibration is directly transferred from the vibrator 503 to the molded product 502. As a result, the molded product 502 can be easily peeled off from the mold 501.
Patent Literature 3 also discloses a similar technique to that disclosed in Patent Literature 2.